The most expensive cars that sold at auction in 2012 didn't have four-wheel drive, but did carry seven- and eight-figure price tags. "There's a growing acceptance of [high-end] cars being seen as very valuable rather than just being seen as being used," says David Brynan of California auction house Gooding & Co. which auctioned off 2012's two costliest cars. "A lot of collectors place cars in same realm as art and antiques these days."

Gooding and other high-end auctioneers reported record sales for high-end car auctions last year despite the world's widespread economic woes. In fact, experts say today's shaky financial markets are prompting more and more ultra-wealthy people to invest in high-end cars. "Rich people see collector cars as a good way to store money," Brynan says. "Someone who's willing to part with $10 million to buy something might want a physical asset that they can see, not just a stock certificate."

"If you're wealthy and you love cars, you might as well have one in the garage that you can enjoy and that will probably appreciate," he says. "You're not really going to get any return if you keep your money in a bank."

Here's a look at the highest-priced cars that sold in 2012 at auctions run by Gooding, RM and other top houses. Listings exclude vehicles sold in private sales, which aren't disclosed to the public

Sixth-costliest car: 1929 Bentley 4.5-liter "Blower" Single-Seater

Winning bid: $8.2 million

This vehicle sold last summer for what's believed to be the highest auction price ever for a British-built car.

Bentley custom-made the racer in 1929 for Sir Henry "Tiger Tim" Birkin, who drove it at Le Mans, Brooklands and the French Grand Prix in the late 1920s and early 1930s.

Birkin was one of a group of wealthy racers known as the "Bentley Boys" because they favored the British brand. ("Tiger Tim" should have stuck to Bentleys. He died in 1933 at age 36 after badly burning his arm racing a Maserati.)

His vehicle got top dollar partly because of its rare equipment mix — a single seat (cars of this type usually had four) and what's apparently the first supercharged engine ever installed on a Bentley. Birkin push the car to 137.96 mph during a 1932 Brooklands meet — a single-lap record at the time for the competition's Outer Circuit course.

Bonhams CEO Malcolm Barber says the vehicle's careful preservation added to its value. "The people who owned this car [after Birkin's death] really kept it as it was, in sort of a time warp of history from the days when it raced," he says. "All too often, cars such as this will lose their character over the years." Alas, the car's new owner will need plenty of money for gas. The model gets only around 2 miles per gallon.

Fifth-costliest car: 1955 Ferrari 410 Sport Berlinetta

Winning bid: $8.3 million

This car is one of four 1955 401 Sports ever built, but has a different body type than the other three.

Ferrari specifically designed its four '55 410 Sports to compete in the five-day Carrera Panamericana road race between Texas and Mexico — although none actually did. The annual race was canceled for decades after the 1955 Le Mans tragedy, where a race car flew into the crowd and killed 83 people.

The 410 Sport that sold at auction in 2012 boasts a mammoth, 345-horsepower V12 engine. But it's the car's design — a coupe for everyday driving instead of an open-topped car for racing — that really boosted its price.

Experts say the vehicle, which famed designer Sergio Scaglietti custom-built for a Ferrari board member, represents an early version of a look that eventually evolved into the legendary Ferrari Testa Rossa. "It's like you went to Ferrari and had them build you a Formula 1 race car but put a [roof] on it so you could drive it on the road," says RM's Girardo, whose firm handled the vehicle's sale.

Fourth-costliest car: 1962 Ferrari 250 GT SWB California Spyder

Winning bid: $8.6 million

Ferrari produced only 106 California Spyders — including just 37 of this prized variant, which combines a short wheel base with covered headlamps.

The convertible also boasts a 280 horsepower V12 engine, three carburetors and four-wheel hydraulic disc brakes — a combination suitable for racing or regular road use.

"The California Spyder is considered the most attractive convertible Ferrari road car in existence, and I'd go so far as to say that it's one of the most-attractive open-topped road cars ever," says Girardo, whose company sold the car.

Late actor and racing enthusiast Steve McQueen used this Ford GT40 to shoot his 1971 classic Le Mans — even though the car doesn't actually appear in the film.

Instead, producers removed its front clamshell section and used the vehicle as a "camera car" where it was driven mostly by racer turned driving school instructor Bob Bondurant. McQueen insisted on shooting all racing scenes at real-life speeds, and very few vehicles could keep up with the film's race cars. The GT40 was one of them and, as a used race car, was worth very little at the time.

One of only three lightweight Gulf/Mirages ever built (just two survive), the GT40 originally featured some of the first carbon fiber parts ever used on cars. That helped the vehicle win the 1967 Spa, Karlskoga and Montlhery races and 1968 Monza 1000 Kilometer run before its use on Le Mans.

Now restored to its original look, the GT40 features a 440 horsepower V8 engine, four carburetors and four-wheel racing brakes. "It's ultimately the best Ford GT40 in existence," says Girardo, whose auction house oversaw bidding for the car.

This car attracted the highest auction price ever for a California Spyder because it's one of just nine with bodies made of lightweight aluminum alloy instead of steel.

"Alloy cars are generally more rare and more prized because they don't survive as well as steel ones," says Gooding & Co.'s Brynan, whose firm auctioned off the vehicle last summer. "They're competition-oriented cars, so they're usually raced or wrecked or things like that."

Although the car's long wheel base makes it less valuable than short-wheeled Spyders, the vehicle does have the covered headlamps collectors prize. It also comes with a rare combination of racing equipment, from a high-performance engine to special brakes.

No. 1 costliest car: 1936 Mercedes-Benz 540 K Special Roadster

Winning bid: $11.8 million

This ultra-rare Mercedes survived Nazi Germany and World War II, then sat in a U.S. garage for decades until its reclusive owner died in 1989. One of the best examples of roughly 15 Mercedes Special Roadsters that still exist, the car belonged originally to Henning and Gisela von Krieger — brother and sister Prussian aristocrats who left Germany to escape the Third Reich.

The von Kriegers managed to ship the car to neutral Switzerland in 1942, then brought it to New York aboard the Queen Elizabeth when they moved to America after the war. Gisela von Krieger, who outlived her brother, left the car in upscale Greenwich, Conn., after she returned to Switzerland. Her old maps, silk gloves and lipstick-stained cigarette butts remained in the vehicle for decades.

The car has an extremely rare chassis and excellent custom-body construction, says Gooding & Co.'s Brynan, whose firm oversaw the vehicle's auction. Now fully restored, the Special Roadster set records this summer for the highest winning bid ever for a Mercedes and any pre-World War II car.

Brynan says a U.S. collector paid top dollar for the vehicle because the car offered a combination of rarity, desirability, good looks and well-documented restoration work. "This vehicle has pretty much everything you'd look for in a collectible car," Brynan says. "Mercedes is known among collectors as the best pre-war [brand], and Special Roadsters are really considered the prettiest and most exotic of them all."